Rubbing Alignment Method for Liquid Crystal Display Panels

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Solution Overview

Problem

The traditional rubbing alignment method for liquid crystal display panels results in uneven alignment and disorientation of liquid crystals due to the formation of rubbing shadows, leading to light leakage and a degraded contrast ratio in the dark state.

Innovation Solution

A two-step rubbing alignment method is employed, where the alignment layer is first rubbed in one direction and then in a direction opposite to the first, ensuring complete coverage and eliminating rubbing shadows, thereby maintaining orderly liquid crystal alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single rubbing process is used on the alignment layer, then the manufacturing process is simple, but rubbing shadows are generated in sunk areas causing uneven liquid crystal alignment

Engineering Contradiction:

Improverubbing process simplicityVSAvoidliquid crystal alignment uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The single rubbing process is segmented into multiple rubbing processes with different rubbing directions. The first rubbing process rubs in a first direction, and the second rubbing process rubs in a second direction that is different from the first direction, ensuring that sunk areas receive proper rubbing coverage and eliminating rubbing shadows while maintaining manufacturing feasibility.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the alignment layer is coated uniformly over all pixels including white sub pixels, then the coating process is simple, but sunk areas are generated due to thickness differences of color resists

Engineering Contradiction:

Improvealignment layer coating simplicityVSAvoidalignment layer surface flatness

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The alignment layer is coated uniformly over all pixels including white sub pixels before the rubbing process. The preliminary coating step ensures complete coverage, and the subsequent multi-directional rubbing processes address the surface flatness issue by eliminating rubbing shadows in sunk areas, maintaining the simplicity of the coating process while resolving the surface flatness problem.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If rubbing shadows are present in the alignment layer, then the rubbing process can be completed quickly, but light leakage occurs in the dark state and contrast ratio is degraded

Engineering Contradiction:

Improverubbing process speedVSAvoiddisplay quality (contrast ratio and light leakage)

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The rubbing process is segmented into multiple passes with different directions. The first rubbing process completes the majority of the alignment in a primary direction, and the second rubbing process addresses remaining rubbing shadows in sunk areas by rubbing in a different direction, ensuring complete coverage and eliminating light leakage issues while maintaining reasonable process efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sunk areas that initially cause rubbing shadows are addressed by utilizing the second rubbing process in a different direction. This converts the harmful effect of sunk areas into an opportunity to ensure complete rubbing coverage, eliminating rubbing shadows and improving display quality without significantly compromising productivity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method effectively suppresses light leakage and enhances the contrast ratio of liquid crystal display panels by ensuring uniform alignment of the liquid crystals, even in areas previously affected by rubbing shadows.

Implementation Method 1

employing the rubbing roller to implement a first rubbing alignment to the alignment layer according to a first rubbing direction... employing the rubbing roller to implement a second rubbing alignment to the alignment layer according to a second rubbing direction

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS10120240B2Rubbing alignment method of alignment layer

Publication Date: 2018.11.06 WUHAN CHINA STAR OPTOELECTRONICS TECH CO LTD

AI summary

The present invention provides a rubbing alignment method of an alignment layer, comprising steps of: step 1, providing a substrate (10), and coating an alignment layer (4) on the substrate (10); step 2, providing a rubbing roller (5), and employing the rubbing roller (5) to implement a first rubbing alignment to the alignment layer (4) according to a first rubbing direction; step 3, employing the rubbing roller (5) to implement a second rubbing alignment to the alignment layer (4) according to a second rubbing direction, and the second rubbing direction is opposite to the first rubbing direction. The rubbing alignment method of the alignment layer can effectively eliminate the rubbing shadow to prevent the uneven rubbing alignment and the liquid crystal alignment disorientation to make the liquid crystals in an orderly arrangement. Thus, the light leakage phenomenon of the liquid crystal display panel in the dark state can be suppressed and the contrast ratio can be raised.